/*
 * Copyright 2009 Griffin Brown Digital Publishing Ltd
 * All rights reserved.
 *
 * This file is part of Probatron.
 *
 * Probatron is free software: you can redistribute it and/or modify
 * it under the terms of the Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * Probatron is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * Affero General Public License for more details.
 *
 * You should have received a copy of the Affero General Public License
 * along with Probatron.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * $Header: /TEST/probatron/com/griffinbrown/shail/expr/LocationPathImpl.java,v 1.1 2009/01/08 14:41:27 GBDP\andrews Exp $
 * $Revision: 1.1 $
 * $Date: 2009/01/08 14:41:27 $
 *
 * ====================================================================
 *
 * Copyright 2000-2002 bob mcwhirter & James Strachan.
 * All rights reserved.
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 
 *   * Neither the name of the Jaxen Project nor the names of its
 *     contributors may be used to endorse or promote products derived 
 *     from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * ====================================================================
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Jaxen Project and was originally
 * created by bob mcwhirter <bob@werken.com> and
 * James Strachan <jstrachan@apache.org>.  For more information on the
 * Jaxen Project, please see <http://www.jaxen.org/>.
 *
 * @version $Id: LocationPathImpl.java,v 1.1 2009/01/08 14:41:27 GBDP\andrews Exp $
 */
package com.griffinbrown.shail.expr;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import org.apache.log4j.Logger;
import org.probatron.jaxen.Context;
import org.probatron.jaxen.ContextSupport;
import org.probatron.jaxen.JaxenException;
import org.probatron.jaxen.expr.Expr;
import org.probatron.jaxen.expr.LocationPath;
import org.probatron.jaxen.expr.Step;

import com.griffinbrown.shail.util.ShailList;

abstract class LocationPathImpl extends ExprImpl implements LocationPath
{
    private List steps;

    private static Logger logger = Logger.getLogger( LocationPathImpl.class );


    /**
     * Create a new empty location path.
     */
    LocationPathImpl()
    {
        this.steps = new LinkedList();
    }


    public void addStep( Step step )
    {
        getSteps().add( step );
    }


    public List getSteps()
    {
        return this.steps;
    }


    public Expr simplify()
    {
        Iterator stepIter = getSteps().iterator();
        Step eachStep = null;
        while( stepIter.hasNext() )
        {
            eachStep = ( Step )stepIter.next();
            eachStep.simplify();
        }
        return this;
    }


    public String getText()
    {
        StringBuffer buf = new StringBuffer();
        Iterator stepIter = getSteps().iterator();
        while( stepIter.hasNext() )
        {
            buf.append( ( ( Step )stepIter.next() ).getText() );
            if( stepIter.hasNext() )
            {
                buf.append( "/" );
            }
        }
        return buf.toString();
    }


    public String toString()
    {
        StringBuffer buf = new StringBuffer();
        Iterator stepIter = getSteps().iterator();
        while( stepIter.hasNext() )
        {
            buf.append( stepIter.next().toString() );
            if( stepIter.hasNext() )
            {
                buf.append( "/" );
            }
        }
        return buf.toString();
    }


    public boolean isAbsolute()
    {
        return false;
    }


    public Object evaluate( Context context ) throws JaxenException
    {
//        logger.debug( "***evaluate() "+getClass().getName() );
        
        ShailList nodeSet = context.getNodeSet();
        
        ShailList contextNodeSet = new ShailList( nodeSet );
        
        ContextSupport support = context.getContextSupport();
        Context stepContext = new Context( support );
        Iterator stepIter = getSteps().iterator();

//        if( logger.isDebugEnabled() )
//            logger.debug( "step count=" + getSteps().size() );

        while( stepIter.hasNext() )
        {
            Step eachStep = ( Step )stepIter.next();

//            if( logger.isDebugEnabled() )
//                logger.debug( "Step=" + eachStep );

            stepContext.setNodeSet( contextNodeSet );
            
//            logger.debug( "setting nodeset for context: stepContext="+stepContext+" contextNodeSet="+contextNodeSet );
            
            contextNodeSet = (ShailList)eachStep.evaluate( stepContext );
            
//            logger.debug( "contextNodeSet evaluated to:"+contextNodeSet );
            
            // now we need to reverse the list if this is a reverse axis
            if( isReverseAxis( eachStep ) )
            {
//                Collections.reverse( contextNodeSet );
//                logger.debug( "reversing "+contextNodeSet );
                contextNodeSet.reverse();
            }
        }

        if( getSteps().size() > 1 )
        {
//            Collections.sort( contextNodeSet, new NodeComparator( support.getNavigator() ) );
//            logger.debug( "sorting "+contextNodeSet );
            contextNodeSet.sort(); //DO WE EVEN NEED A NODECOMPARATOR? -- check behaviour with NamespaceNodes!!
//            logger.debug( "SORTED="+contextNodeSet );
        }
        return contextNodeSet;
    }


    private boolean isReverseAxis( Step step )
    {

        int axis = step.getAxis();
        return axis == org.probatron.jaxen.saxpath.Axis.PRECEDING
                || axis == org.probatron.jaxen.saxpath.Axis.PRECEDING_SIBLING
                || axis == org.probatron.jaxen.saxpath.Axis.ANCESTOR
                || axis == org.probatron.jaxen.saxpath.Axis.ANCESTOR_OR_SELF;
    }

}
